Region locking, for all you kids out there, is exactly what it sounds like: certain consoles or games are 'locked', therefore only allowing you to only access it in that particular region. Due to globalization, the video game industry has moved beyond locking out certain games in certain regions, but Nintendo has lagged behind in that regard.
But perhaps for not much longer. In a forum post, courtesy of NeoGAF, Nintendo president Satoru Iwata expressed sentiments that the company may be moving away from the antiquated DRM process.
"The game business has a history of taking a very long time with localization among other things, such as having to deal with various issues of marketing in each particular country," said Iwata, "or games that have made use of licensed content that did not apply globally, and had all kinds of circumstances, so to say, that region-locking has existed due to circumstances on the sellers' side rather than for the sake of the customers."
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Nintendo was the first company to create the notion of region locking for video game consoles, back in the 1980s with the original Nintendo. The Japanese and North American/European systems had a different pin configuration in the cartridges, disallowing Japanese titles to be played on other systems.
"As for what should be done going forward, if unlocked for the benefit of the customers, there may also be a benefit for us."
There are several million Wii U's in circulation in all regions, so removing the region lock would be a process (even if it's a matter of rewriting code). "Conversely, unlocking would require various problems to be solved, so while I can't say today whether or not we intend to unlock, we realize that it is one thing that we must consider looking to the future."
Nintendo is working towards region-free, having released several titles, such as Pokemon X and Y last year. When and if Iwata moves ahead with plans to unlock the systems, the Wii U will join both PS4 and Xbox One in being region-free.